气候变化领域集成服务门户(CCPortal): Skill of dynamical and GHACOF consensus seasonal forecasts of East African rainfall

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DOI	10.1007/s00382-019-04835-9
	Skill of dynamical and GHACOF consensus seasonal forecasts of East African rainfall
	Walker D.P.; Birch C.E.; Marsham J.H.; Scaife A.A.; Graham R.J.; Segele Z.T.
发表日期	2019
ISSN	0930-7575
起始页码	4911
结束页码	4935
卷号	53 期号:2020-07-08
英文摘要	Seasonal forecasts of rainfall are considered the priority timescale by many users in the tropics. In East Africa, the primary operational seasonal forecast for the region is produced by the Greater Horn of Africa Climate Outlook Forum (GHACOF), and issued ahead of each rainfall season. This study evaluates and compares the GHACOF consensus forecasts with dynamical model forecasts from the UK Met Office GloSea5 seasonal prediction system for the two rainy seasons. GloSea demonstrates positive skill (r = 0.69) for the short rains at 1 month lead. In contrast, skill is low for the long rains due to lack of predictability of driving factors. For both seasons GHACOF forecasts show generally lower levels of skill than GloSea. Several systematic errors within the GHACOF forecasts are identified; the largest being the tendency to over-estimate the likelihood of near normal rainfall, with over 70% (80%) of forecasts giving this category the highest probability in the short (long) rains. In a more detailed evaluation of GloSea, a large wet bias, increasing with forecast lead time, is identified in the short rains. This bias is attributed to a developing cold SST bias in the eastern Indian Ocean, driving an easterly wind bias across the equatorial Indian Ocean. These biases affect the mean state moisture availability, and could act to reduce the ability of the dynamical model in predicting interannual variability, which may also be relevant to predictions from coupled models on longer timescales. © 2019, The Author(s).
英文关键词	Consensus outlooks; East Africa; Precipitation; Probabilistic verification; Seasonal climate forecasts
语种	英语
scopus关键词	atmospheric dynamics; climate variation; easterly wave; forecasting method; precipitation assessment; precipitation intensity; probability; seasonal variation; Indian Ocean
来源期刊	Climate Dynamics
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/145945
作者单位	School of Earth and Environment, University of Leeds, Leeds, United Kingdom; National Centre for Atmospheric Science, Leeds, United Kingdom; Met Office Hadley Center, Exeter, United Kingdom; College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, United Kingdom; IGAD Climate Prediction and Applications Centre, Nairobi, Kenya
推荐引用方式 GB/T 7714	Walker D.P.,Birch C.E.,Marsham J.H.,et al. Skill of dynamical and GHACOF consensus seasonal forecasts of East African rainfall[J],2019,53(2020-07-08).
APA	Walker D.P.,Birch C.E.,Marsham J.H.,Scaife A.A.,Graham R.J.,&Segele Z.T..(2019).Skill of dynamical and GHACOF consensus seasonal forecasts of East African rainfall.Climate Dynamics,53(2020-07-08).
MLA	Walker D.P.,et al."Skill of dynamical and GHACOF consensus seasonal forecasts of East African rainfall".Climate Dynamics 53.2020-07-08(2019).